Ultrasound is a useful technique for ranging, or the measurement of distance to an object of interest, and is especially important for environmental sensing on mobile platforms. Ultrasound distance detection involves an ultrasound wave that is transmitted from an ultrasound source to the object of interest. The ultrasound wave reflects from the object of interest and is transmitted back to the ultrasound source. Since sound has a relatively constant velocity, a travel time for the ultrasound pulse to reflect from the object of interest and return to the ultrasound source is directly proportional to the distance between the source and the object. Thus, by measuring the travel time of the ultrasound pulse, the distance can be determined.
Since distance detection requires accurate identification of a reflected ultrasound wave (or “echo”), the presence of background noise can lead to misidentification of the echo and faulty distance detection. The problem of background noise is especially acute for mobile platforms that rely on mechanical motion—for example, propellers on unmanned aerial vehicles (UAVs)—for movement, since such mechanical motions can cause strong high-frequency sounds that are detected with the echo. Resulting waveforms received by the ultrasound transceiver can therefore be difficult to de-convolute. Existing techniques for noise reduction often fail under such circumstances.
In view of the foregoing, there is a need for systems and methods that more robustly separate signal from noise for ultrasound distance detection.
It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of the preferred embodiments. The figures do not illustrate every aspect of the described embodiments and do not limit the scope of the present disclosure.